Electrode for gaseous conduction lamps and method of making same



1932- F. SCHAEFER ET AL 1,874,124

ELECTRODE FOR GASEOUS CONDUCTION LAMPS AND METHOD OF MAKING SAME Filed Aug. 19, 1929 Fateimteel Aug. SG, 393% UNITED STATES PATENT OFFICE FRANK SCHAEFER, OF KALAMAZOO, AND 3A. S. DUFFENDACK, OF ARBOR,

MICHIGAN ELECTRODE FOR GASEOTJS CONDUCTION LAMPS AND METHOD OF MAKING SAME Application filed August 19, 1929. Serial No. 886,812.

In the manufacture of gaseous conduction lamps it has long been recognized that one of the difiiculties is the disintegration of the electrodes in use which has a deleterious ef- 5 feet upon the life of the tube and also variation in the gas within the lamp, thereby affecting the electric discharge. It has been attempted to minimize this disintegration by employing electrodes having a relatively large surface area. This is only a partial remedy as even such electrodes disintegrate under certain conditions and the results are imperfect and other disadvantages are incident to the use of such electrodes.

The main objects of this invention are: First, to provide an electrode for gaseous conduction or luminous tube lamps which is highly efiicient in the matter of electric dis-- charge, may be made in relatively small dimensions or have a small surface,-and at the same time does not sputter or disintegrate in use.

Second, to provide an electrode which is not materially affected by the heat or long continued use.

Third, to provide a method of making electrodes for gaseous conduction lamps and the like by which great uniformity of results may be had, and electrodes economically produced 3 having the above recited and other advantages.

Objects relating to details and economies of our invention will appear from the description to follow. The invention is defined and pointed out in the claims.

A structure which is a preferredemb odiment of our invention is illustrated in the accompanying drawing, in which:

Fig. 1 is a fragmentary side view of a gaseous tube lamp embodying our improved electrode.

Fig. 2 is a detail view mainly in longitudinal section on line 22 of Fig. 1;

Fig. 3 is an enlarged view of the electrode.

Fig. 4 is an illustration of one of the steps in making the electrode.

Referring to the drawing, 1 represents a gaseous tube lamp and 2 one of the electrodes thereof. This electrode is provided with a lead-in wire 3.

The electrode 2 is made in accordance with our improved method which consists in grinding or otherwise reducing to a finely divided state a metal which we for convenience designate as base metal, such as nickel, copper or aluminum, and also grinding or otherwise reducing to a finely divided state barium oxide or the oxide of an alkali or metal of the alkaline earth groups. Highly satisfactor results are secured when nickel is employe for the base metal with barium oxide, although other base metals or their oxides may be very satisfactorily employed.

The proportions of these elements may be very considerably varied but the base metal should be present to such an extent as to act as a binder, holding the mass together.

The mixed elements are pressed into a solid preferably into the desired size and shape of the electrode. If the elcmentsare pressed into a larger mass than desired for the electrode, the electrodes are shaped from the solid mass and subjected to heat in the air or in an oxidizing atmosphere, preferably such a degree of temperature as will cause surface fusion to a substantial depth.

In Fig. 4 we illustrate the heating step, the electrode pellet being subjected to oxyacetylene flames indicated at 4.. Where barium is employed, the barium is converted or mainly converted to barium oxide.

Compounds of the alkali or alkaline earth metals other than oxides may be employed in the making of electrodes by this method with satisfactory results.

Our improved electrode may be easily outgassed as they are of such carrying capacity that they may be of small size and at the same time are not subject to sputtering.

Having thus described our invention, what We claim as new and desire to secure by Letters Patent, is:

1. The method of making electrodes for gaseous conduction lamps consisting of mixing finely divided round nickel oxide and barium oxide, pressing into a solid, and subjecting to a suflicient degree of heat in an oxidizing atmosphere to produce substantial surface fusion.

2. An electrode of the class described comprising a mixture of finely divided barium oxide and finely divided nickel oxide solidified into a coherent mass and having a black homogeneous fused surface.

3. An electrode of the class described comprising a solidified coherent mixture of finely divided base metal and an alkali or alkaline earth metal oxide fused on the surface.

4. An electrode of the class described comprising a mixture of finely divided base metal and finely divided alkali or alkaline earth metal solidified into a coherent mass and fused on the surface.

5. An electrode of the class described comrising a coherently solidified mixture of a nely divided base metal oxide and a finely divided alkali or alkaline earth metal and having a fused surface.

6. An electrode of the class described comprising a coherently solidified mixture of fine- 1y divided base metal and finely divided barium having a fused homogeneous surface. In witness whereof We have hereunto set our hands.

FRANK SCHAEFER. ORA S. DUFFENDACK. 

